Effect of pressure on the electrical resistivities of some ternary rare earth compounds

Electrical resistance of sintered samples of ternary compounds of the rare earths having tI 10 ThCu2Si2 structure are determined from measurements in an Bridgman anvil apparatus upto 80 kbar. The resistance measurements were performed using d.c. four-probe technique. In CeCu2Si2 and YbCu2Si2 the rare earth atom is known to exist in an intermediate valence state and in compounds CeAu2Si2 and CeAg2Si2 it is expected to go over to an intermediate valence state on application of pressure. Such a valence state transition is not expected in LaCu2Si2. In LaSi2Cu2 the resistance drop is small. In all cerium compounds the small initial drop is followed by an increase in resistance at high pressures due to the magnetic contribution, while in other compounds it remains constant. Large resistance drop in compounds CeCu2Si2 and YbCu2Si2 may be indicative of a valence change transition under pressure. (auth.)